Many moons later and I’m back to a need for this! Sorry for the delay, and I’m still finding this to be an issue. I think the issue lies in spinning up something else that is also watching/reacting/etc. from Dash. I think this post is similar and my need, I think, is bigger than just writing a status to a file.
I’m trying to make a user interface for some Robot Operating System (ROS) code. ROS enables many nodes to co-exist and communicate on things called topics. An analogy might be something like a webserver that can do GET/POST. I’ve been hoping to combine these things into one, but am having a tough time.
So imagine you have some other library and need to create an object listening/publishing on some other port… maybe:
foo = Server(port)
foo.start()
In addition, perhaps periodically you do foo.publish().
What I’m finding is if I initialize this up with app = dash.Dash(__name__), it recreates with any page refresh, so I get errors due to the node already existing. I can put some checks in a function like your example, but I don’t know how to pass foo around to run foo.publish().
Do you have recommendations of where to create some object you need to interact with, (assuming that this server analogy makes sense and is possible with Dash)?
Also, for a secondary process, how does one kill off everything when you kill Dash?